Flow measurements in dialysis shunts: lack of agreement between conventional Doppler, CVI-Q, and ultrasound dilution.

BACKGROUND: Measuring flow in dialysis shunts is recommended to predict imminent thrombosis. Multiple methods for measuring blood flow are in use. Numerous ultrasound protocols exist which determine volume flow using a conventional Doppler (CD) frequency shift analysis technique. All of these are subject to potentially large errors. Quantitative colour velocity index (CVI-Q) does not make use of the Doppler equation and is more precise in vitro. Ultrasound dilution (UD) measures access flow during dialysis in a non-operator-dependent way. The aim of the present study was to compare these three methods of measuring access flow in vivo for agreement with each other. METHODS: In 38 accesses flow was measured by CD, CVI-Q, and UD. All measurements were done during dialysis. Agreement was determined by intraclass correlation coefficient (ICC=R(i)) and Bland-Altman analysis. RESULTS: ICC between UD and CVI-Q was R(i)=0.56. ICC between UD and CD was R(i)=0.10, and ICC between CD and CVI-Q was R(i)=0.16. Bland-Altman analysis revealed a bias (mean difference) of -38 ml/min between UD and CVI-Q, a bias of 1129 ml/min between UD and CD, and a bias of 1167 ml/min between CVI-Q and CD. CONCLUSIONS: CD measurements did not agree with UD or CVI-Q much higher values were recorded with the former than with the latter two techniques. The agreement between UD and CVI-Q measurements is low but reasonable. Caution must be applied in comparing and interpreting values of access flow measured by different techniques.

[Renal insufficiency due to light chain multiple myeloma]. / Nierinsufficiëntie door neerslag van lichte ketens bij multipel myeloom.

In 3 female patients, aged 65, 83 and 76 years, with severe renal failure, light chain multiple myeloma was diagnosed, following a substantial delay on the part of the doctors concerned. Either the diagnosis had not suspected or the serum proteins had been misinterpreted. After a while, the first two patients declined further treatment with chemotherapy and haemodialysis, and subsequently died. The third patient attained a creatinine clearance of 20 ml/min and was subsequently treated for the multiple myeloma in the outpatients department. The absence of a paraprotein peak in the serum does not exclude the possibility of a multiple myeloma. In the case of light chain disease, the gammaglobulin region is, in fact, often empty. Treatment of multiple myeloma consists of a rapid rehydration and forced diuresis; the usefulness of plasmapheresis has not been demonstrated.

Spontaneous hypoglycaemia in chronic renal failure.

Spontaneous hypoglycaemia in renal failure occurs more frequently than is considered generally. The pathogenesis is complex. Understanding the underlying mechanisms is of interest to all practitioners attending patients with renal failure. A case report is presented describing a patient with 'spontaneous' hypoglycaemia, without any illness other than renal failure. The various mechanisms contributing to or causing hypoglycaemia are reviewed.

Pharmacokinetics of epoetin in haemodialysis patients after subcutaneous administration: influence of chronic treatment.

The purpose of this study was to investigate whether chronic subcutaneous administration of epoetin has an influence on its pharmacokinetics in patients with chronic renal failure and anaemia. 14 Patients were included in the study. The data of 8 patients could be evaluated at the end of the study. All patients were on maintenance haemodialysis. The pharmacokinetic profile of epoetin was studied directly after the first subcutaneous administration of 60 U/kg body weight. Patients were further treated with epoetin to maintain haemoglobin concentration between 6.0 and 6.5 mmol/l. After about one year of treatment the pharmacokinetic profile was studied again, using the same dosage. Between both profiles no significant differences (paired Student's t-test) were found in the pharmacokinetic parameters studied: absorption half-life, time to maximum concentration, maximum concentration, elimination half-life, area under the curve and mean residence time. However, in individual patients large differences may be found.

[Hypomagnesemia and chondrocalcinosis]. / Hypomagnesiëmie en chondrocalcinosis.

A female patient aged 45 years is described with a rare form of chondrocalcinosis caused by hypomagnesaemia due to excessive renal loss of magnesium. The patient also had impaired renal conservation of potassium leading to a hypokalemia. She most probably had an idiopathic renal tubular dysfunction. Magnesium supplementation prevented further symptoms. Therefore in young patients with chondrocalcinosis it can be of therapeutic importance to search for an underlying treatable metabolic disorder.

Effect of immunomodulator thymopentin on impaired seroresponse to influenza vaccine in patients on haemodialysis.

In a double-blind placebo-controlled multicentre study, the effect of the immunomodulator thymopentin (TP5) on the antibody production to trivalent influenza vaccine was tested in 108 patients on chronic intermittent haemodialysis (HD). Antibody production was determined in pre- and postvaccination sera. Compared to a group of 35 young healthy adult control subjects, HD patients showed a clearly impaired seroresponsiveness to all three vaccine components, regardless of treatment with TP5 or placebo. We conclude that TP5 administration is not able to enhance humoral immunity in patients on chronic intermittent HD.

Long-term follow-up of the polytetrafluoroethylene (PTFE) prosthesis as an arteriovenous fistula for haemodialysis.

During a 10-year period vascular access in 86 patients receiving long-term haemodialysis was provided by the insertion of 100 polytetrafluoroethylene grafts. In 24 patients (28%) the PTFE prosthesis was used as a primary access operation; 62 patients (72%) had had previous access procedures. Early thrombosis and infection led to graft failure in eight patients. Late fistula occlusion developed in 67 instances in 39 fistulae. Thrombectomies were performed in 53 fistulae with good result in 46 (86.8%). Infection after puncture was seen in nine grafts and was treated by incision and drainage (33%) or graft removal (67%). False aneurysms developed in six patients; prolonged haemorrhage from the puncture site occurred in one patient and haemodynamic complications (ischaemic steal syndrome; venous hypertension) developed in four. The cumulative patency of PTFE AV fistulae was 74% after 1 year; 59% after 2 and 3 years and 47% after a follow-up of 5 years. Despite the high rate of complications the PTFE AV fistula has proved an acceptable technique in secondary access surgery for haemodialysis.

Intact humoral immune response in patients on continuous ambulatory peritoneal dialysis.

After influenza vaccination no statistically significant difference in antibody response was observed between patients on continuous ambulatory peritoneal dialysis (CAPD) and healthy volunteers while a large group of hemodialysis (HD) patients was found to have a significantly lower response rate. This difference remained statistically significant when CAPD patients were compared to a matched HD group. As the antibody formation after influenza vaccination is a T cell-dependent phenomenon, the normal immune response to vaccination suggests an intact humoral and cellular immunity in CAPD patients.

Formation of leukotriene B4, 20-hydroxy leukotriene B4 and other arachidonic acid metabolites by macrophages during peritonitis in patients with continuous ambulatory peritoneal dialysis.

Macrophages, isolated from dialysis fluid of three patients with continuous ambulatory peritoneal dialysis (CAPD) at different times during peritonitis were labelled with 14C-arachidonic acid and stimulated with the calcium ionophore A23187. The main metabolites formed by 5-lipoxygenase activity were leukotriene B4 (LTB4) and 5-hydroxy-6, 9, 11, 14-eicosatetraenoic acid (5-HETE). Smaller amounts of cyclooxygenase metabolites were present and also a major compound with an elution time between 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TxB2). This substance was isolated, analyzed by GC-MS and identified as 20-hydroxy-leukotriene B4 (20-OH-LTB4). This indicates that human peritoneal macrophages obtained from CAPD not only produce leukotrienes and prostaglandins, but also the omega-hydroxylase product of LTB4, which has been demonstrated to be present in polymorphonuclear leucocytes. The activity of this enzyme was not correlated with the severity of the peritonitis.

Trivalent influenza vaccine in patients on haemodialysis: impaired seroresponse with differences for A-H3N2 and A-H1N1 vaccine components.

One hundred and one patients on haemodialysis, 21 patients on peritoneal dialysis and 30 healthy controls received a trivalent split vaccine containing 15 micrograms haemagglutinin of a recent influenza A-H3N2, influenza A-H1N1 and influenza B strain, respectively. Antibody production after four weeks was determined by the haemagglutination-inhibition test and expressed as response rate, protection rate and overall mean fold increase. The patients on haemodialysis revealed a diminished seroresponse, as compared to patients on peritoneal dialysis and controls. For influenza A-H3N2, this was less distinct than for the other two antigens. In patients on haemodialysis the protection rate was 66% against the A-H3N2 vaccine component (versus 85% in controls, not significant), but only 25% against A-H1N1 and 27% against B (versus 84 and 77% in controls, p less than 0.001). Duration of haemodialysis up to eight years did not affect seroresponse. Patients on haemodialysis who were primed for influenza A-H1N1 in the period 1947-1957, reacted markedly better to the A-H1N1 vaccine component than subjects of other priming periods. A booster injection of the same vaccine dosage four weeks after the first immunization, performed in 98 patients on haemodialysis, was of little value: it had virtually no effect with regard to influenza A-H1N1 and influenza B, and showed, though significantly better, still poor results for A-H3N2. The differences in seroresponse between the A-H3N2 and A-H1N1 vaccine component suggest a major defect of primary, and a minor defect of secondary humoral response in patients on haemodialysis. The consequences for vaccine policy in these patients are discussed.

Oxalosis in chronic renal failure.

The incidence and severity of oxalate deposition as a complication of chronic renal failure in a retrospective study of 73 patients is presented. The reason for this study was the occurrence of a syndrome characterised by multiple shunt-complications, muscle weakness and peripheral ulceration in three haemodialysis patients. This syndrome seems to be caused by an obliterative vasculitis due to oxalate deposition in the media of peripheral vessels (Figure 1).